I have read a lot of threads with similar questions, but after reading the answers, I am very confused. I have found in them lots of url's with repositories but people discusses about which repositories are made for one or two versions of ubuntu, but I have found nothing about 11.10 version. Is too soon to ask for that? Should I downgrade my ubuntu to have a realtime kernel?

4 Answers
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The long term goal of the RT kernel project is to end up having all the RT functionality in the standard kernel, and this is progressing nicely. The RT patch has had irregular releases in the past, and the hacking of kernel.org in August 2011 made the 3.0 version inaccessible for months, but now things are looking good: there's a patch for 3.0, another for 3.2 (coinciding with the kernel versions in Ubuntu 11.10 and 12.04), and another for 3.4, see here.

If you are using Precise, you can use Alessio Bogani's Realtime PPA, who has kindly packaged the vanilla kernel with the RT patch applied and is keeping it in sync with the version numbers in Precise.

If you prefer to build the RT kernel by hand, first install the required software packages:

where you should select "full preemption" (option 5) when prompted, and leave everything else at its default value by pressing enter at every prompt. The config from the -lowlatency kernel might be a better starting point than that of the -generic kernel.

You should be able to reboot into your RT kernel at this point.
If your kernel fails to boot make sure you double-check the boot parameters, and edit them accordingly in your bootloader. For example, ACPI functions may affect your real time system (as stated on rt.wiki.kernel.org). Adding acpi=off may be a solution in such case.

Notice though that the RT patch is incompatible with the Nvidia binary driver (but see the post by user "rt-kernel" below, and this question for a workaround), and that the Ubuntu kernel patches will not be present, so you may have hardware problems that you did not have before. This is true of both the PPA packages and the compiled kernel. You can always boot into your -generic kernel and uninstall the realtime kernel packages if they give you trouble, of course.

I could not run the compiled kernel following these instructions. So instead of the vanilla kernel from kernel.org, I downloaded Ubuntu's linux-source package using apt and it worked successfully then.
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MelebiusMar 18 '14 at 10:18

If you depend on using the nvidia binary driver you can patch the original driver with this patch (for 3.4+ kernels with rt-patches only) This patch comes with no garantee or warranty! Use it on your own risk.->

Neat. Does the patched nvidia driver work with -generic too? It'd be useful to know how to produce a .deb instead of using the installer.
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pablommeApr 16 '12 at 15:18

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Your patch is missing four spaces at the start of the line elif [ "$ARCH" = "ARMv7" ]; then and the one after -- it won't apply if this is not fixed. Also, you might want to mention that the nvidia driver version 295.33 can be downloaded from nvidia.com/object/linux-display-amd64-295.33-driver.html (it's not the latest any more, but judging by a report at phoronix.org from earlier today it may be better not to use 295.40 for the time being).
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pablommeApr 17 '12 at 0:17

sudo is missing from the installation command, as well as indication that you need to switch to a VT and do sudo killall Xorg && sudo stop lightdm before executing it because it insists that X must not be running. Other than that, everything works nicely -- now I can avoid bug bugs.launchpad.net/bugs/920120 and run dual-screen Ardour \o/ Thanks for the patch!
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pablommeApr 17 '12 at 2:14

This has nothing to do with the question, am I wrong?
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Bruno PereiraNov 27 '12 at 15:04